BUREAU OF ENGINEERING
of the
DEPARTMENT OF PUBLIC WORKS
CrY AND COUNTY OF SAN FRANCISCO
CALIFORNIA
Hetch Hetchy Water Supply
By
M. M. O'SHAUGHNESSY
Member American Society, C. E.
CITY ENGINEER, SAN FRANCISCO
OCTOBER 1925
BUREAU OF ENGINEERING
OF THE
DEPARTMENT OF PUBLIC WORKS
CITY AND COUNTY OF SAN FRANCISCO
CALIFORNIA
HETCH HETCH Y WATER SUPPLY
M. M. O'SHAUGHNESSY
MEMBER AMERICAN SOCIETY, C. E.
CITY ENGINEER, SAN FRANCISCO
V
OCTOBER I925
Digitized by the Internet Archive
in 2012 with funding from
California State Library Califa/LSTA Grant
http://archive.org/details/hetchhetchywaterOOosha
HETCH HETCHY PROJECT
Foreword
The past three years have been marked with strenuous activity toward the
completion of the Hetch Hetchy Water and Power Project of San Francisco, which
will be capable of furnishing the water supply for a population of 4,000,000 people
when the construction storage works in the high Sierras have been completed.
Five key dams stand completed, two of which — the O'Shaughnessy Dam and the
Lake Eleanor Dam, hold back an aggregate amount of water greater than all the
reservoirs of Los Angeles and San Diego massed together.
Twenty miles of aqueduct tunnels have been completed in the high Sierras,
while at the westerly end of the project Spring Valley water is being passed since
September 12, 1925, through the Bay Crossing Aqueduct, 22 miles in length. The
right-of-way for the aqueduct measures the width of the State and over this right-of-
way the transmission towers have been erected which carry electric energy from the
Moccasin Power Plant to the gates of San Francisco.
Since August 14, 1925, the Moccasin Power Plant has been put into service
and is now furnishing the greater portion of the power used to light the homes of
San Francisco and drive the wheels of its factories. This has been made possible
through a contract entered into with the Pacific Gas & Electric Company under
which that company is employed as the temporary distributor of San Francisco's
power output. The City received for the power delivered in San Francisco during
the month of September, $182,426.97, or at a rate somewhat in excess of $2,000,000
annually. On this basis the net revenue from the power, after paying operating
expenses, and the $250,000 per annum to be received from the Spring Valley Water
Company for the temporary use of the Bay Crossing Aqueduct, amounting to
$1,900,000, will pay the interest at V/ 2 per cent on $42,000,000 of bonds, which is
more than is now outstanding on the entire project.
The gap remaining to be completed in the water supply portion of the project
is the tunneling and laying of pipe from Moccasin Power House, through the
mountains that mark the San Joaquin, Livermore and Santa Clara Valleys, to
(rvington terminal. The work in the Foothill Division is now actually under way.
The purpose of this outline is to enlighten the public generally concerning this
•vater and power project, which is the greatest asset that San Francisco possesses,
ind to these this report is respectfully submitted.
M. M. O'Shaughnessy,
City Engineer.
San Francisco, California, October, 1925.
HISTORY OF
HETCH HETCHY WATER
SUPPLY
By M. M. O'Shaughnessy, City Engineer
EARLY SOURCES OF SAN FRANCISCO'S WATER SUPPLY
AN FRANCISCO'S earliest water supply was taken from wells within
the City, and ten million gallons daily are still obtained from this
source. Such wells, however, soon became inadequate, and for a time
it was necessary to import additional water in barges from across the
Bay, and to distribute it by means of water wagons.
In 1858, a company known as the San Francisco Water Works, instituted a
pressure pipe water service, the source being Lobos Creek, which drains the north-
westerly portion of the present City. A second company, the Spring Valley Water
Works, brought water three and one-half miles from Islais Creek in 1861, and the
following year increased its supply by taking from Pilarcitos Creek, 32 miles away.
The two companies combined in 1865, under the name of the second, which, in 1903,
reorganized as the Spring Valley Water Company.
Under the single management, the sources were gradually added to; San
Andreas and Crystal Springs reservoirs in San Mateo County were constructed, and
pipe lines were built connecting them to the City.
The Peninsular supply was added to in 1888 by the completion of two sub-
marine pipe lines crossing San Francisco Bay and bringing in water from Alameda
Creek. The capacity of the pipe line was increased in 1902,- and a booster pumping
station added in 1913, bringing the present Spring Valley yield capacity up to about
42 million gallons daily — twenty million from the Peninsula and twenty-two million
from the Alameda County sources.
The Spring Valley Water Company acquired, through all those years, over 100,000
acres of land. After a complete survey in 1915, the City Engineer, with the approval
of the Railroad Commission, as a basis for purchase by the City, excluded all but
61,560 acres of land as being necessary for water purposes. In San Francisco
County there remains for City use 913 acres, in San Mateo 22,817 acres, Alameda
County 24,220 acres, and in Santa Clara 13,610 acres.
On the 17th of April, 1922, an agreemnet, sanctioned by the Railroad Com-
mission, was made between the Water Company and the City for the development
of an additional 24 million gallons daily by the Company's reconstruction of the
Calaveras Dam, Niles Canyon concrete conduit, and 16,000 feet of 44-inch pipe
from Niles to Irvington. The City agreed to spend $5,000,000 of the Hetch Hetchy
funds in building 22 miles of conduit, consisting of 5-foot diameter pipe — capacity
for delivery under Hetch Hetchy conditions of 43 million gallons daily — from
Irvington, through Pulgas Tunnel, to Crystal Springs Reservoir. As consideration
for the lease of this conduit by the Water Company the City receives an annual
5
rental of $250,000. Under the same agreement, the City holds an option good until
December 31, 1933, to purchase the Water Company's system and the lands enumerated
above for $38,000,000.
THE HETCH HETCHY PROJECT IN A NUTSHELL
The Hetch Hetchy Project is one to provide an adequate municipal water supply,
evolved by the City and County of San Francisco, after a thorough and comprehensive
study of all possible sources. The general plan contemplates the collection and
storage of waters of the Tuolumne River and its tributaries near their sources in
the Sierra Nevada Mountains, and the transmission of those waters across the San
Joaquin Valley and through the Coast Range Mountains for delivery to the
City of San Francisco and its environs; due advantage being taken of appropriate
drops in the conduit routes for the generation of the maximum quantity of hydro-
electric power which can be economically developed.
HISTORY
The project had its beginning back in 1901, when the Mayor of the City filed
water appropriations on the Tuolumne River and its tributaries, Cherry River and
Eleanor Creek. These appropriations were kept alive by preliminary development
work until a permit was obtained from the Federal Government for the acquisition
of storage reservoir sites situated on public lands within the limits of the Yosemite
National Park (not Yosemite Valley). This was granted by Secretary of the
Interior Garfield in 1908 relative to lands and waters tributary to the Tuolumne
River in the northern part of the Park and twenty miles distant from the Yosemite
Valley proper, which latter is drained by the Merced River. Having secured this
permit, San Francisco proceeded to acquire, at an expense of $1,915,000, all privately
owned lands in the Hetch Hetchy Valley and the rights and holdings of William
Ham Hall, John Hays Hammond and others on the Tuolumne and Cherry Rivers and
on Eleanor Creek, a tributary of the Cherry. With the accession of the Ballinger
administration in the Interior Department, a movement was started by certain coteries
of so-called "nature-lovers," and others, to revoke that portion of the Garfield permit
relating to the Hetch Hetchy Valley, which was the largest of the proposed reservoir
sites. Secretary Ballinger went out of office after having issued an order directing
San Francisco to show cause against this revocation. President Taft ordered an
investigation and report by a Board of United States Army Engineers, consisting
of Colonel John Biddle, Lieutenant-Colonel Harry Taylor and Major Spencer Cosby.
This board of engineers examined exhaustively all alternative sources of supply
which had been suggested as available for San Francisco's use, including the
Stanislaus, Calaveras, Mokelumne, Cosumnes, American, Yuba, Feather, McCloud,
Sacramento, Eel, and San Joaquin Rivers, and the local sources of the Spring Valley
Water Company. The Army Engineers' report, made to Secretary Fisher, Mr.
Ballinger's successor, under date of February 19, 1913, recommended the use of
the Hetch Hetchy Valley and the Tuolumne supply as being not only the most
available but the cheapest and most economical for the City's use and affording the
greatest hydro-electric development possibilities. Previous to the report of this
board of engineers, the City had an exhaustive examination of all available sources
made by John R. Freeman, an engineer of national repute, associated with the water
supplies of Boston and New York. He strongly recommended the Tuolumne source
as the best and outlined the scheme of development which, with some necessary
modifications, is now being followed.
After taking testimony and examining all reports submitted, Secretary Fisher
gave it as his opinion that Congress alone had the power to grant the privileges
sought by the City. After a great deal of argument before Congress, the Hetch
Hetchy grant was passed by both Houses and signed by the President on December
19, 1913. This act was framed on the recommendation of Secretary Lane of the
Interior Department and Secretary Houston of the Department of Agriculture, and
by it Congress (Stats. 1913, p. 242) granted forever to the City rights in 420,000
acres of the public domain.
The water rights have, from their inception, been carefully protected and title
to the same is fully vested in San Francisco under the provisions of the Civil Code
of California. Antecedent to this, on January 14, 1910, the people of San Francisco,
by a vote of 32,886 for and 1,609 against, authorized the issuance of $+5,000,000 of
bonds for the construction of the project.
Actual work was commenced as soon as the Congressional grant was obtained.
Surveys were completed, many miles of wagon road were constructed, a standard
gauge railroad 68 miles long was located and built, the floor of Hetch Hetch Valley
was cleared of timber, a sawmill was installed and put in operation, diamond drill
borings were made at the main damsite and along the line of the tunnel aqueduct,
a construction power plant was built, together with a dam at Lake Eleanor, storing
nine billion gallons to carry the plant through the dry season, and an aqueduct to
supply the plant with water. Twenty-two thousand volt transmission lines connect
it with all working points on the tunnel aqueduct, camps and warehouses. Head-
quarters buildings were constructed, and work has been completed on the Mountain
Division, including the O'Shaughnessy Dam at Hetch Hetchy, the Mountain Aqueduct,
Priest Dam, power tunnel, pressure pipes, Moccasin Power House, and tower line
for transmission of electrical energy to San Francisco as far as Newark.
During the period of the war the City carried on work with a force of from
400 to 500 men, with due care always not to interfere with the selective draft or
the nation's need for materials and equipment. Progress was necessarily not as
rapid as would otherwise have been the case. Sound economic reasoning dictated
that the Mountain, or power-generating, division, of the project be completed first,
in order that the burden upon San Francisco's taxpayers of paying interest during
construction might be reduced by revenue from power at the earliest possible
moment. The dominant purpose of the project is, however, water supply, and
every effort must be made to complete the water conduits without unnecessary delay
in order to remedy the water shortage from which San Francisco has long been
suffering.
OUTLINE OF THE PRINCIPAL ENGINEERING FEATURES
The space afforded in this resume suffices for only a brief description of the
principal engineering features of the project. For convenience the work has been
divided into ten divisions, known as the Lake Eleanor, Hetch Hetchy, Mountain,
Priest, Moccasin, Foothill, San Joaquin, Coast Range, Bay Crossing and Peninsula
divisions. Surveys, geological and engineering studies have so far been conducted
over the entire work and construction done on all divisions except the San Joaquin
and Coast Range.
ORGANIZATION
The 'Hetch Hetchy development is one of the activities of the Department of
Public Works of the City and County of San Francisco. The City Engineer is
Chief Engineer of the project, and the Chief Assistant Engineer has direct charge
of the work. Two construction engineers, located at Groveland and at Palo Alto,
report to the Chief Assistant Engineer. Legal matters are handled by special counsel
and rights-of-way by a right-of-way agent.
M. M. O'Shaughnessy, City Engineer
The staff consists of:
General
M. M. O'Shaughnessy, City Engineer Chief Engineer
N. A. Eckart, Chief Assistant Engineer
City Office Engineers
L. W. Stocker Assistant Engineer
R. P. Mcintosh Hydraulic Engineer
R. J. Wood Structural Engineer
P. J. Ost Electrical Engineer
E. P. Jones Mechanical Engineer
Construction Engineers
L. T. McAfee Construction Engineer, Groveland
C. R. Rankin Construction Engineer, Palo Alto
L. A. McAfee Assistant Engineer, Groveland
J. H. Ryan Assistant Engineer, Groveland
A. J. Wehner Assistant Engineer, Groveland
L. B. Cheminant Assistant Engineer, Groveland
A. B. Johns Assistant Electrical Engineer, Groveland
General Office Staff
Robert M. Searls Special Counsel
Jos. J. Phillips Right-of-Way Agent
H. W. Kephart Purchasing Agent
The following are among the experts who have acted as consultants at different
times on the project:
Frank G. Baum Electrical Engineer
Dr. Wm. F. Durand Mechanical Engineer
Dr. Jas. C. Branner Geologist
John D. Galloway Civil Engineer
Professor Chas. D. Marx Civil Engineer
Professor Charles Wing Civil Engineer
PROGRAM ADOPTED
In starting any business enterprise it is of the highest importance that the
income which is to support the enterprise should commence as early as possible, so
that the interest and other fixed charges on the investment shall not be a dead-
weight on the investors any longer than absolutely necessary.
In the case of the Hetch Hetchy Project, it required only the construction of
the main storage dam and the upper 20 miles of the aqueduct to reach the 1300-foot
power drop at Moccasin Creek. Hence the decision was made to concentrate all
energy and financial resources on the works above the Moccasin Creek power plant
site for the two-fold purpose of developing and protecting our water rights and
producing an income from hydro-electric energy that could be applied to reduce the
burden of interest and bond redemptions during the later construction of the aqueduct
between Moccasin Creek and San Francisco.
With the greatly advanced prices of labor and materials resulting primarily
from the World War, exceeding pre-war prices by 70 per cent, and the wider scope
of the project as evolved under the Hetch Hetchy grant, and also on account of the
necessity of selling bonds at a substantial discount for several years, the completion
of the units mentioned will exhaust the funds realized from the $45,000,000 bond issue
of 1910. The completion of the aqueduct will require money to be obtained from
further issuance of bonds, but the revenue from power sales and from the Spring
Valley Water Company will meet, to a very large extent, the interest on the new
bonds; so the wisdom of the course adopted is thus apparent.
Construction Begun
Hetch Hetchy Water Supply Contract No. 1, awarded July 8, 1914, covered the
grading of nine miles of 22-foot roadway from Mather to Hetch Hetchy, which
hitherto had been accessible only by trail. The road was completed in March, 1915.
A diversion tunnel 20 feet in diameter, to deflect the main Tuolumne River, was
then excavated in the south wall of the Hetch Hetchy gorge around the damsite.
Timber clearing was commenced in the reservoir area, and borings were made at
the damsite to determine the depth to bedrock in the river bottom.
Up to the present date, 106 public contracts for all features of the work,
aggregating $25,000,000, have been awarded by the Board of Public Works after
appropriations have been made by the Board of Supervisors, based on open bidding
9
on plans and specifications prepared by the City Engineer. There has been no
breath of scandal or insinuation of any kind relative to any of these contracts or
any other phase of the work.
Railroad
To transport equipment and materials to Hetch Hetchy Dam, the aqueduct
tunnels and the power plant, a standard gauge railway was built on grades not
exceeding 4 per cent and on curves not exceeding 190-foot radius, extending along
the entire upper end of the work in the foothill and mountain divisions. The
Hetch Hetchy Railroad, 68 miles in length, connects with the Sierra Railway at
Hetch Hetchy Junction, 26 miles from the town of Oakdale, and extends to O'Shaugh-
nessy Dam.
Hetch Hetchy Ra
I. Tuolumne River Bridge
Starting at Hetch Hetchy Junction, at an elevation of 935 feet, the route leads
across rolling country and descends into the Tuolumne River Canyon to 600 feet
elevation. It then follows up the river, crossing it on a steel bridge below Jackson-
ville. At Moccasin Creek a steep climb begins, and continues until elevation 3070 is
attained at mile 26, near the headquarters town of Groveland. From this point
east the line follows generally the dividing ridge between the Tuolumne and Merced
Rivers. Thence the general elevation increases until at mile 62 the summit is reached
— Poopenaut Pass — at elevation 5064. Six miles of continuous descent on a 4 per
cent grade complete the 68 miles to Damsite, where the elevation is 3870 feet.
The last nine miles of the railroad was built on the roadbed previously graded and
used as roadway.
The railroad serves the working points of the 30 miles of main aqueduct east
of the Sierra Railway, the Moccasin power development, and the City's sawmill,
some directly, others through short spur tracks, tramways, or motor truck hauls.
Haulage from the railroad is generally in the downhill direction.
Snowplow at Mather Station,
Hetchy Railroad
Early Intake from Heteh Hetchi
Railroad
The railroad was commenced in 1916 — with over 1,000,000 cubic yards excava-
tion, and completed in October, 1917. It was operated from July, 1918, to February,
1925, as a common carrier. Freight rates were on a basis of 12^ cents per ton
mile for carload lots for all freight except lumber and livestock, on which commodity
rates were established. The basis of passenger fares was iy 2 cents per mile.
The cost of construction of the railroad was about $3,000,000. The early use of
the road enabled the City to complete the O'Shaughnessy Dam in April, 1923, in
three and one-half years, and thereby gave San Francisco priority to the flood
waters of the Tuolumne River.
The completion of the Don Pedro Reservoir by the Turlock and Modesto
Irrigation Districts necessitated the relocation of the Hetch Hetchy Railroad at the
Six Bit Gulch crossing, the old trestle at this point being four feet below the flow
line of the reservoir. The trestle was replaced by a nine-span plate girder bridge,
585 feet long, 15 feet higher in elevation than the old trestle. The reconstruction
of this bridge and the relocation of adjacent stretches of track were made on request
of, and were paid for, by the two irrigation districts.
Sawmills
Sawmill machinery was purchased in August, 1915, and a sawmill erected at
Canyon Ranch, five miles from Hetch Hetchy. After six million board feet of
lumber had been sawed at this location, the supply was exhausted and the sawmill
moved to Mather. At Mather it continued to operate until the winter of 1923-1924,
when, having served the needs of the present construction, its operation was dis-
11
Construction Power House at Early Intake. General view showing forebay
flume, penstock and building.
continued. Lumber from the mill was used for concrete forms, camp buildings,
flumes, tunnel timbering, and miscellaneous structures. High-grade lumber, such as
sugar pine and white pine, not required in the City's work, was traded to privately
operated mills to advantage for cheaper woods. A total of 21 million feet B. M.
was cut.
LOWER CHERRY POWER SYSTEM
To operate construction equipment in the mountains, a 3000 K. V. A. power
plant was installed near the mouth of the Cherry River. The construction was
commenced in the summer of 1916, and completed, ready for operation, in June, 1918.
Water for this installation is diverted from Cherry Creek into a conduit of 200
second feet capacity, 3.3 miles long, consisting of 1.2 miles of tunnels, 1.1 miles of
flumes, and 1 mile of concrete lined canals. The power house contains three turbines,
operating under a maximum head of 345 feet, fed by a 42-inch pipe line 530 feet
long, each direct connected to a 2300 volt, 1000 K V. A. generator. Power is
transmitted at 22,000 volts 11 miles east to O'Shaughnessy Dam and 22 miles west
to Moccasin Creek, supplying intermediate substations along the line. Since the
completion of Moccasin power plant the Cherry aqueduct has been extended one-
half mile to Early Intake Diversion Dam so that the Lake Eleanor water can be
passed through the main aqueduct to Moccasin.
This system has furnished power for all the Hetch Hetchy Water Supply
activities as required, except the main sawmill drive; and surplus power has been
sold to the Pacific Gas & Electric Company through a connection at Priest. Two
interruptions of power operation from February 25, 1922, to April 21, 1922, and
from February 25, 1923, to March 14, 1923, resulted from landslides carrying away
portions of the open concrete lined canal, and one from November 28, 1921, to
December 18, 1921, from a shortage of water. Those breaks caused serious loss in
Power House at Early Intake. Interior showing three Pelton Francis
turbines direct-connected to 1000 K.V.A. generators
the continuous operation of the work until a dependable outside standby service was
connected up. During such interruptions power was drawn from the Pacific Gas &
Electric Company system to supply the westerly end of the work.
LAKE ELEANOR
To permit the operation of the power plant during the low water season, it was
necessary to develop a certain amount of storage at Lake Eleanor. The construction
of Lake Eleanor Dam was commenced in August, 1917. It was put in service in
June, 1918. The dam is 1260 feet long and 70 feet in maximum height. It contains
11,640 cubic yards of concrete, heavily reinforced. It is of the buttressed arch
type, with several original features developed by the City Engineer's studies.
There are 20 arches, each with a span of 40 feet. These arches are on an incline
of 50 degrees to the horizontal and are supported by buttresses. The dam is curved
in plan. One interesting feature to the engineer is that the cross-section of the
arches follows a circular arc on a horizontal plane, and an elliptical arc on a
Lake Eleanor multiple arch dam which impounds 27.S00 acre feet
normal plane, which is the reverse of the usual construction heretofore used in this
type of dam. Over the entire length of the dam is a reinforced concrete roadway,
12 feet wide.
The stored water is withdrawn through two 24-inch sluice gates, placed on
the face of the dam.
The dam was completed late in 1918, but had already been put to use for
storage of water to operate the Lower Cherry power plant. The entire cost of the
15
O'Shaughnessy Dam. Deepest point of excavation for foundation, 118 feet below bed
Tuolumne River. Outline of dam shown by white lines on the rock
structure, including a 12-mile wagon road from Hetch Hetchy costing $28,000, was
about $320,000.
The flow line of the reservoir created by the dam is at elevation 4660 feet,
and its capacity is about 27,800 acre-feet, or nine billion gallons. This quantity is
only a small part of the annual runoff from the Lake Eleanor watershed, and the
reservoir is filled each year early in the flood season.
O'SHAUGHNESSY DAM
The contract for the construction of the first installment of the O'Shaughnessy
Dam across the Tuolumne River at the outlet of Hetch Hetchy Valley, was awarded
after open bidding August 1, 1919, to the Utah Construction Company.
The dam is of the arched gravity type — 700-foot radius — built of cyclopean
concrete (concrete in which are imbedded large blocks of stone ranging in size from
about one cubic foot to five or six cubic yards).
When the water supply or electric power requirements demand, the dam will
be raised to its ultimate height and thickness. So great is the present-day demand
for hydro-electric power, and so constantly is it increasing, that the completion of
the last addition will probably be governed by power needs rather than consideration
of the water supply.
All foundation work below stream level for the ultimate structure has been
completed with the present construction.
When it becomes necessary to add to the reservoir capacity developed by the
initial dam, the dam will be brought up to its full ultimate size by adding a thickness
of 80 feet on the downstream face of the initial dam and building up 85 feet higher.
This will make available 80 feet additional depth of reservoir, and will make the
messy Dam. The heavy valve section in the center is full thickness for the
tlam when built to its ultimate height 85 feet above the present crest
lake 300 feet deep at the dam. The total height of the dam above the foundations
will then be 430 feet. This is higher than any dam now in existence.
The initial dam has a height above the original stream bed of 226.5 feet, and
a maximum height above foundations of 344.5 feet, and contains 398,516 cubic
yards of concrete. The length on the crest is 605 feet and the thickness on the crest
is 15 feet. The thickness of foundation is 298 feet. The present wasteway consists
of 18 spillways of the siphon type, discharging over the downstream face of the
dam.
The floor of Hetch Hetchy Valley has been cleared of timber, in order to protect
the impounded waters from contamination due to the decay of submerged timber.
Valves for Outlet System
Valves to control the discharge of water for irrigation and domestic use through
the dam as required, have been installed at various levels. Openings, designated as
supply pipes, supply wells, and discharge conduits, have been cast in the concrete as
the structure was built.
The valves consist of the following:
Six 5-foot balanced needle valves;
Six 3-foot balanced needle valves ;
Six 47-inch by 90-inch slide gates ;
Six 33-inch by 42-inch slide gates.
The valves and their appurtenances comprise over two million pounds of
metal of high-grade design, and cost nearly $700,000.
On each opening through the dam there are two controls. The water is admitted
through the hydraulically operated slide gate to the supply well and from there the
required flow is regulated and discharged by the balanced needle valves. These
valves are of the latest type of hydraulically balanced valve which permit manual
control of a plunger weighing five tons, under a high head of water. The water
discharges in an annular ring surrounding the plunger.
The six 5-foot balanced valves and the six 47-inch by 90-inch slide gates are
installed in the main portion of the dam, being set in the concrete as the structure
advanced. Three of the 3-foot balanced valves are installed on the lower side of
the dam at elevation 3625, in a special valve house, and have three 33-inch by 42-
inch gates installed in the dam in connection with them. Three 36-inch needle
valves and three 33-inch by 42-inch slide gates are installed in the concrete plug
in the diversion tunnel and permit draining the reservoir to its lowest levels. All
sluice gates can be made accessible for repairs by closing the inlet tunnels by means
of steel shutters in concrete slots.
Spillway
The temporary spillway of the initial dam consists of 18 siphons, each 4 feet by
10 feet at the throat, and placed in three series at slightly different levels. The
siphon openings are heavily reinforced with steel. Each siphon has a capacity of
approximately 1,000 cubic feet per second. The spillway has operated successfully
since May 25, 1923, when the reservoir first reached its flood limit. The water
discharging from the siphons down the steps on the back of the dam forms a water-
fall of imposing appearance.
It is the plan, on the final completion of the dam to full height, to bypass the
floods through canals and tunnels at either end past the abutments of the dam so
as to clear the structure altogether, and plug the existing siphons with concrete.
18
Roadway on Dam
The top of the dam is finished with a 17-foot roadway, on the sides of which
are placed precast concrete railings, which add an artistic finish to the structure.
A concrete girder bridge connecting the dam to the Eleanor road harmonizes
with the main structure. The east abutment of the bridge is on roller bearings to
provide adjustment to meet temperature changes and consequent movement in the
arched dam.
* J
HETCH HETCHY WATER SUPPLY of THE city and COUNTY OF SAN FRANCISCO. CALIFORNIA .
O'SHAUGHNESSY DAM
AT
HETCH HETCHY VALLEY
CROSS SECTIONS SHOWING PRESENT AND FUTURE DAMS.
Department of Public Works. ////// /if\/ yvv. M4AU*h, „
approved, UM/\Uv* jL,i ^r^^\/ City Engineer
BV <US? TRACED OS*? CHECKED
SCALE As shown DATE June IZ 192^.
*Ww
A 287,
Construction Methods
In order that the foundation of the dam might be constructed in the dry, a
rock-filled timber crib dam was built above the location of the main dam, and a
concrete backwater dam 800 feet downstream, thus passing the water around the
damsite through the diversion tunnel which had been enlarged to 23 feet by 25 feet.
Excavation down to 65 feet below streambed was accomplished with steam shovels
and dump cars; below that level derricks and skips were used.
At elevation 3439 at the downstream toe, bedrock was encountered and a concrete
retaining wall, 31 feet in height, was built, sealing off all seepage into the lowest
portion of the foundation. At the upstream toe, on reaching an elevation of 3435
feet, a cofferdam was sunk to bedrock, elevation 3399, and a concrete retaining wall
was poured, cutting off practically all seepage into the excavation.
After removing all material overlying the granite bedrock, this was roughened
to receive the concrete. A sand-blast was used in places to roughen the glazed and
polished surfaces of the pot holes in the water-worn rock formed by pre-historic
cascades from ancient glaciers. This provided a clean, rough surface for bonding
the concrete.
Concrete was placed with chutes from a wooden, four-compartment hoisting
tower, 375 feet high, built on the south side of the canyon. After the forms were
removed, a coating of gunite was applied to the upstream face.
During the cold weather period each year from December to March, a heating
Hetch Hetchy Reservoir. View east showing central three miles of r
Rock on right, rises 1SO0 feet above floor of valley
plant, consisting of a large steam boiler and circulating pipes, was installed to
prevent the concrete from freezing.
Large stone, or plum rock, was placed in the cyclopean concrete to an amount
not exceeding 8 per cent of the mass.
Rock for concrete was crushed in a plant located on the valley floor upstream
from the damsite. Sand was excavated about three miles upstream from the
damsite and hauled to the work on a 3-foot gauge construction railroad, with ten
locomotives, and there screened, stored and reconvened to the mixers. Plum rock
was taken from the talus slopes on the north side of the valley and hauled one
mile to the dam on flat cars. Cement in bulk was unloaded from cars on the
Hetch Retchy Railroad into a bin above the dam, and conveyed to the mixers by
gravity.
Concrete placing began in September, 1921, and finished in February, 1922;
398,516 cubic yards being placed.
The dam was completed in May, 1923. The cost of construction by the Utah
Construction Company was $6,121,000. On May 24 the reservoir was completely
filled and the siphon spillway began discharging the flood waters.
A turbine generator and storage battery were installed in the bypass tunnel to
supply power to meet local requirements at O'Shaughnessy Dam when the existing
transmission line from Early Intake to the dam is removed.
EARLY INTAKE DIVERSION WORKS
The water released from Hetch Hetchy reservoir flows, for the present, 12 miles
down the Tuolumne River to Early Intake Diversion Dam. Eventually, it will
flow through a 12-mile tunnel and a power house developing 60,000 horsepower
and be discharged above the diversion dam. The water from Lake Eleanor, which
now flows down Eleanor Creek, Cherry River, and the Lower Cherry aqueduct
about 10 miles to the diversion dam, eventually will be carried in an aqueduct
about 11 miles long to a power house in the Tuolumne River Canyon about one
mile above Early Intake, where 40,000 horsepower will be generated. The water
released from the plant will flow down the river channel with the water from
Hetch Hetchy and be diverted into the tunnel aqueduct which begins at Early Intake.
The diversion dam consists of a thin concrete arch 262 feet long and a concrete
spillway 130 feet long. On the left bank is the aqueduct intake tower with gates
regulating the flow of water for San Francisco's use. Water in excess of that
diverted to San Francisco and necessary to supply the Turlock and Modesto
irrigation districts will pass over the spillway to flow down the Tuolumne River
about 40 miles to Don Pedro Reservoir.
The diversion dam has an upstream radius of 100 feet. Thickness at crest at
elevation 2356 is 6 feet, at base 16 feet. Height above river-bed is 55 feet and the
base extends 26 feet down to solid granite. On the south, the arch abuts the granite
canyon wall; on the north is a concrete block containing 3611 cubic yards. From
this block the spillway extends northerly, divided by piers into five sections, each
23 feet long, in which automatic radial gates have been installed, whose function is to
maintain the water surface at elevation 2346, or 5 feet above the lip of the spillway.
Tunnel invert at inlet is at elevation 2326 feet. A siphon arrangement automatically
lowers these gates to pass excess floods and allows them to rise after the flood has
subsided. In constructing the arch section of the dam, two vertical openings with
keyways 18 inches wide, were left at the points of approximate zero bending
21
Moonta/n Dws/on
Tonne/ '. /g.g m/'/es
to fh/est ffeservo/,
£/erat/'on
Crest ofJJam Z3J6 ft.
*- 3ottom of /vt/natof/bo ZZ75 ■
% Funnet /nvert 2.326 •
(^ So, >//H>ay £/p Z34I »
tVorma/ M&ter Jt/rface Z344> ■■
HETCH HETCHY WATER SUPPLY OF THE CITY AND COUNTY OF SAN FRANCISCO, CALIFORNIA
EARLY INTAKE DIVERSION DAM
GENERAL PLANI
IOO 30 O IOO
Scale of Feet
Department of Public Works, approv
BY__UBX i __TRACED__LB.£__CHECKED_/»
SCALE.. _As.._.sb.nv*o DATE__.Ju.ae 4. iszs
ol&Ay^
-City Enoinkcr
A 280.
moment until the dam had taken final set. Then in the extreme cold weather, when the
dam had received final set, these keyways were filled with concrete.
The gate tower at the intake is equipped with fixed grillage outside, to catch
heavy refuse; and wire mesh, manually operated, traveling screens inside, to catch
tunnel to Prie
nn. View up Tuolumne River. Flume on left discharges water
Sherry River. Gatehouse on right is the inlet to the 18.8-mi"
. Spillway on left, with automatic gates, bypasses flood waters
leaves and light refuse. Sand chambers in front of the screens discharge through
the dam. There are 9 sluice gates, 4 feet by 5 feet, 5 in the lower tier and 4 in
the upper. These are set in a thin reinforced concrete arch of 16 feet radius abutting
on the rock wall of the canyon. A concrete house covers the operating wheels,
screen mechanism, etc., the whole structure being protected from falling rocks from
the adjacent mountainside by a reinforced concrete guard wall on the uphill side
of the intake. The dam, spillway and gate structure contain 16,564 cubic yards of
concrete.
Mountain Division Tunnels
The Mountain Division Tunnels extend 18.8 miles from here to Priest Reservoir.
The first half mile of tunnel skirting under the canyon wall is 14 feet 3 inches high
by 13 feet 4 inches wide, with top arched to 6 feet 8 inches radius, bottom to 20
feet 5 inches radius, has 166.5 square feet neat excavation, and is unlined, except
for a few short stretches. The next seven miles, also unlined, is excavated to
13 feet 6 inches high by 13 feet 4 inches wide, with top arched to 15 feet radius and
bottom to 20 feet 5 inches, with neat arta 167.8 square feet. This section is
interrupted near mile No. 5 by 225^4 feet of 9 feet 6-inch diameter riveted steel
pipe, which carries the flow across the south fork of Tuolumne River. The pipe is
a continuous beam of four unequal spans, the longest being 74 feet across the main
channel, and is supported on concrete piers whose reinforcmeent extends into holes
drilled in the bedrock. An expansion joint is introduced at the point of contraflexure
23
JJ1
- a)
nearest the upstream anchor. The pipe is covered with heavy timber to prevent
damage from rocks falling from the cliffs above.
The remainder of the tunnel, about 11.3 miles, is lined throughout with l:2%Ay^
concrete with minimum thickness of 6 inches.
This tunnel is of horseshoe shape 10 feet 3 inches high by 10 feet 3 inches wide,
of 87.94 square feet net area inside of lining. The rock encountered consisted of
sect/on /, coA/cffrrz t_/t\tf£>.
Anv, ins/ate concrete 07.94 if ft
• excavat/en, ant/mbered /of. 63
, timbered t33.f *
fifcaraf/on perfoof:
L/ntimberea '■ ^3.91 z cuy
Umbered -« ?■*
Cone re /e per /do/
t/n timbered '■ .655
Timbered - / .39
Actt/a/ ai/eraqe for
//.3 mi/es - Z.04
y5fCr/OA/S , Mt/M£0.
Area , sq.ft. /6&5
Excavation per
foot, a/ yds 6.17
Note - This section used
on/y for the "ft/Version
Tcnne/, joj~/ ft. /or?^ t
at fc/r/y //jfake .
SECT/ON 'of-, t/MJN£D.
Area ■ ■ 1 67. s sq.ft.
"ion per foot- 6.ZI cuydj.
HETCH HETCHY WATER SUPPLY or the city AND COUNTY OF SAN FRANCISCO, CALIFORNIA
STANDARD TUNNEL SECTIONS
USED IN
HETCH HETCHY AQUEDUCT
Department of Public Works, approved
-£&?:
-TRACED, Jt*?* .CHECKED
mt(
:liJ^A s ^^^.
SCALE_.~jnch.£.L_fDot... DATE Jure 9,1925.
City Engineer
A 282
26
diorite, quartzite, slate and amphibolite schist. The tunnel with a grade of 0.00155,
or about 8 feet per mile, has a capacity of 620 second feet.
Excavation was carried on from 12 working faces: one at each end portal, one
on each side of the stream crossing, four from two adits and four from two shafts.
The first heading was begun at the south fork Tuolumne River crossing, July 7,
1917, proceeding easterly. Big Creek shaft was opened in February, 1918, and
tunneling begun from 575 feet below the collar in August, 1919. The shaft was
646 feet deep. Second Garrote shaft, 786 feet deep, was begun in November, 1918,
but encountered excessive amounts of water as high as 2,000 gallons per minute,
which delayed its completion until December, 1922. The last connection in driving
the 18.8-mile tunnel was made between Big Creek shaft and Second Garrote shaft
on November 26, 1923.
Muck car trains in the tunnels were hauled by electric storage battery locomotives.
Electric mucking machines were used at all headings except while working out from
Big Creek and Garrote shafts, which were too small to allow the convenient
passage of the electric machines. At these headings smaller air operated mucking
machines were used. A spare machine was maintained at each camp to insure
continuity of service. Electrically driven air compressors and blowers were used
at all the camps. At Second Garrote shaft a steam driven air compressor was
maintained for standby service to insure against failure of electric power supply.
The rate of progress varied according to the formation, from 300 to over 700
feet per month. The best record for one month was 776 feet, made from the Priest
(west) portal of the tunnel. This established a new United States speed record for
hard rock tunnel driving.
Tunnel lining was begun with one plant on March 20, 1923; after April, 1924,
two plants were working and completed the lining in May, 1925. The total distance
lined is 60,630 feet.
PRIEST REGULATING RESERVOIR
At the west tunnel portal at elevation 2170 the water enters Priest Reservoir,
created to provide forebay capacity for the fluctuating demand of the Moccasin power
plant. The reservoir was made by constructing an earth fill dam with concrete core
wall across Rattlesnake Creek. This forebay reservoir contains 2350 acre feet, or over
two days' flow of the tunnel. Priest Dam is 1160 feet long and 145 feet high. Crest
width at elevation 2245 is 20 feet. The dam is 660 feet thick at its base and contains
717,283 cubic yards of earth and rock fill and 17,043 cubic yards of concrete in the
core wall, which extends 15 feet deep into bedrock. To provide a certain degree
of flexibility the core wall is divided into panels 50 feet long by 16 feet high, water
stops of 16 gage copper being placed in the joints between panels. Some 27 tons
of copper are used in the structure for this purpose.
The embankment consists of rock spoil from the tunnels placed in the up and
downstream toes, earth fill placed by hydraulic methods and earth fill placed by
dump cars from steam shovel and sluiced into place by water jets. The slope of the
upstream face is iy 2 to 1 ; downstream face is 2 to 1 slope except the rock toe,
which is l}i to 1. The upstream face is riprapped to prevent erosion from wave
action.
A concrete lined spillway 40 feet wide, with lip at elevation 2240, protects
against overtopping. An outlet and drainage tunnel 6 feet in clear diameter, with
inlet at elevation 2120 feet, was driven through the solid rock of the east abutment
and lined with 12 inches of concrete. Valves in the tunnel are reached by a vertical,
28
Priest Dam. View down Rattlesnake Creek. Track in left center marks outlet of
18.8-mile tunnel. Power Tunnel begins near sheds in right center
Priest Regulating Reservoir. Dam at left. Gatehouse in upper right is at entrance to
Power Tunnel which is 95 feet below high water. Mountain Division Tunnel discharges
near house in right center, 70 feet below high water
circular concrete tower of 6 feet inside diameter. The tunnel and tower contain 1954
cubic yards of concrete. The dam was begun in January, 1922, and completed in
August, 1923.
Moccasin Power Tunnel
Water discharging from the reservoir to the power house enters Moccasin
Power Tunnel at elevation 2145 through a concrete control tower, oval in plan,
£/er. z/z&ydaxifiary Ot/t/et Tunnet
6mdeZZ2Z{ 6'dio., 97J ' /ova,tf?rvi/(?h bed rocA
ce/jt
/Reinforced concrete
6a fe Tower
Sca/e of feet
fba J of ts.8 mis. tunnet from
( Ear/y /nfa/re ,£/er. 2//o'.
^-^Sc]^- / n / et of
PRIEST DAM
Area inside concrete
Area of excavation,
ant/rnbered tjf.9B :
Excavation per f/'neat
foot 6..5Z c
Concrete, -do- t.27
' , actual average
for Jt33fi ft. J.So cuyc
MOCCASIN POWER TUNNEL
METCH HETCHY WATER SUPPLY OF the city and county of SAN FRANCISCO. CALIFORNIA
PRIEST DAM
AND
MOCCASIN POWER TUNNEL
CROSS 5E.CTI0NS / /
Department w Public Works, approved ^(/CCC-^/A^j^U^O^/ City Cnoineer
BY. -£*5^.. TRACED. £«*?, . CHECKED .$?M 9 :- 9 " A OO C
SCALE. As. shown. .. DATE Jrjrie 12, 1925 . /ACO^.
30
65 feet by 36 feet, inclusive of semi-circular, precast screen rack projecting into the
reservoir. The structure contains 2765 yards of 1:2:4 concrete. Six electrically
operated sluice gates, each 6 feet by 8 feet, provide for cutting off water to the
tunnel. Manual operation is also possible and steel shutters are provided for
isolating any set of gates for repairs, if necessary. Fixed screens with manually
operated cleaner prevent fine trash from entering the tunnel.
The tunnel begins as the frustum of an oblique cone tapering from about 19
feet width and height to 13 feet standard section in a distance of 30 feet. The
tunnel section is 141.47 square feet with grade of 6 feet per 1000, making its
capacity 1240 second feet without excessive loss of head. The minimum thickness
of concrete inside of timbering is 9 inches; the concrete averages 3.8 cubic yards per
lineal foot. The tunnel extends 5370 feet to the inside wall of a surge shaft 40 feet
in diameter, which serves as a manifold for the three penstock pipes, which are
imbedded in concrete in tunnels 535 feet long, leading from the opposite side toward
the power house.
Surge Shaft
The surge shaft is designed to handle surges of from 35 to 40 feet. The floor
is at tunnel grade, elevation 2112, and the height to the rim is 160 feet. It projects
48 feet above the surface of the ground. The walls of this portion range in thickness
from 24 inches to 10 inches and contain heavy reinforcement, the maximum of
which is two rings of 1^2-inch square bars staggered at 7-inch centers. Accumulation
of external water pressure below the ground surface which might result from
surface runoff, is prevented by a system of porous cement drain tile. The shaft
contains 2185 cubic yards of 1:2:4 concrete.
Penstock Pipes
The three penstock pipes, the horizontal length of which is 5349 feet, begin at
the wall of the surge shaft, each as the frustum of an oblique cone with large
diameter 12 feet 4 inches. The smaller end connects to the 104-inch diameter riveted
steel pipe. About 50 feet westerly from the tunnel portal in each line a 10+-inch
diameter butterfly valve has been installed. The most southerly pipe is dead-ended
at the valve pending future extension when two more generators shall have been
installed in the power house. The butterfly valves are motor operated and arranged
for closing by remote control from the power house. As a matter of precaution the
opening control is at the valve only. Two sets of four 8-inch air valves are installed
in each line immediately below the valves.
The thickness of pipe plate at the surge shaft is >^g-inch. At elevation 2070
the diameter reduces to 98 inches and the double riveted lap joints change to triple
riveted butt. At a slope distance of 2111 feet the pipes branch each into two 66-inch
diameter pipes of hammer forge welded steel with "bumped" joints of enlarged section,
reducing obstruction to stream flow of rivet heads. The welded pipes whose slope
length is 3469 feet, range in diameter from 66 to 54 inches and in thickness from
7/16-inch to 1 5/16-inch. Immediately before entering the power house the four
54-inch diameter pipes branch each into two 36-inch diameter pipes in which are
installed in an arcade of the power house hydraulically operated 36-inch gate valves.
The total weight of pipe is 12,487,709 pounds, the heaviest section of pipe weighing
approximately 26,000 pounds. The 30-foot lengths are supported on some 400 concrete
piers, or saddles, built in advance of the pipe-laying. At angles, of which there
are 20, either horizontal, vertical or combined, the pipes are held securely by concrete
anchors, the largest of which contains 839 cubic yards of concrete and 7.64 tons of
reinforcing steel. Expansion joints are provided between anchors. At the 98-inch
31
by 66-inch "Y" branch is a special sliding anchor in which the upper portion,
inclosing the pipes, can slide on cast iron plates imbedded in the fixed concrete of
the lower portion.
Moccasin Power Plant Penstocks at west end of Power
Tunnel. In upper center is the surge shaft where the
tunnel divides and pipes begin
MOCCASIN POWER PLANT
This power plant, the largest of the Hetch Hetchy system, uses the full flow
of the aqueduct, 620 second feet, dropping from 2240 feet, the elevation of high
water in Priest Reservoir, to 924 feet, the elevation of the water wheel nozzles.
The power house, as at present built for four units, is 225 feet long, 98 feet
wide and 67 feet high. It is a steel frame building, with massive concrete foundations
and with reinforced concrete walls. The architecture is of the California-Spanish
style, which is particularly suited to the site. This building houses the generators
and low voltage switching apparatus, but the step-up transformers, high tension
switches and high tension busses are installed in the rear, out-of-doors, at the easterly
side of the building. The busses are carried on a structural steel frame. The 11,000
32
volt, 3-phase, 60-cycle current generated, is stepped up to 115,000 volts for trans-
mission to San Francisco. All apparatus, however, is designed for operation at
154,000 volts.
The water wheels were manufactured by the Pelton Water Wheel Company
of San Francisco. These are of the double over-hung impulse type and operate at
257 r.p.m. Each has a rated output of 12,500 h.p., or 25,000 h.p. for the unit. The
rotating part of each unit weighs 118 tons and can be handled by the 135-ton crane
installed in the power house. The static pressure head at the power house is 1316
feet. The water wheel rating is, however, based on an effective head of 1250 feet.
The maximum jet diameter is 11 inches. An auxiliary relief needle nozzle is set
directly beneath the main nozzle and connected therewith in such manner that it may
be operated as a synchronous bypass, or may be set to close automatically to save
water.
The generators and exciters were furnished by the General Electric Company.
The rating of the generators is 20,000 K.V.A. These generators deliver 11,000
volts directly to the transformers, the arrangement of the power house being such
that so far as practicable the generators and the transformers operate together as a
unit, provision being made for but one 11,000-volt bus, which can be used to connect
any generator to any bank of transformers in an emergency. From this 11,000-volt
bus all auxiliary power is taken for use in the operation of the station, and for two
22,000-volt circuits for construction work along the aqueduct line.
The transformers, switchboards and switches were supplied by the Westinghouse
Electric and Manufacturing Company. The transformers are single phase, 6667
K.V.A. capacity, with taps which permit of their being operated at either 11,000 to
115,000 volts, or 11,000 to 154,000 volts. They are set out-of-doors in banks of three;
complete piping connections are provided for circulating water and for oil filling
and filtering. Tracks and transfer cars permit of any transformer being moved into
the power house under the crane for repairs.
From the switching station behind the power house, two 154,000-volt circuits
will be carried to San Francisco on one double circuit steel tower line. The
electric transmission line at the present time has been built as far as Newark on
San Francisco Bay, a distance of 9% l / 2 miles from the power house; 506 towers are
employed in this distance — an average spacing of 1,000 feet. They are placed on
the northerly boundary of a 110-foot right-of-way strip, to be supplemented in the
future with a similar line on the southerly side. The distance between lines is 24
feet at the top arm, 28 feet at the middle arm, and 24 feet at the bottom arm.
The vertical spacing between conductors is 15 feet. The lowest cross-arm is 62
feet above the ground. The conductors from the power house to a point within a
few miles of the bay are 397,500 cm. steel reinforced aluminum conductors. From
the point where bay fog is encountered, hemp cored copper conductors are used.
These have a circular mil capacity of 345,000, with an external diameter of ^-inch.
At suspension points, 10 units of Westinghouse No. 601 insulators are used, while at
dead-end and other points of stress, 12 Westinghouse No. 631 insulators are employed.
Operation of the present two circuits in parallel, as will normally be the case,
will permit of transmitting the power generated at the Moccasin plant with a line
loss of approximately 8 per cent, and when one line must be taken out of commission
temporarily, the remaining circuit will still have capacity to transmit the output
of the plant to San Francisco.
34
FOOTHILL DIVISION
The plan for the aqueduct to San Francisco calls for 17 miles of tunnel in the
Sierra foothills below Moccasin Creek, the tunnel being divided into two sections at
the Tuolumne River by the Don Pedro Reservoir at Red Mountain Bar. The
reservoir is crossed by an inverted steel pipe siphon cased in concrete. This
construction was not required for several years to come, but as the river channel at
the crossing was to be flooded by the reservoir constructed by the irrigation districts
of Turlock and Modesto, the lower portion of the siphon submerged by the lake was
constructed in advance of filling the reservoir.
This section, with the ends extending well above the elevation of the dam crest,
is of riveted steel pipe, 9 feet 6 inches in diameter and 771 feet long. The thickness
of the steel varies from ^-inch to 9/16-inch. The interior of the pipe is lined with
cement mortar 2%. inches in thickness, leaving the net diameter 9 feet \y 2 inches.
The pipe is laid on bedrock and is incased in concrete from 18 inches to 2 feet in
thickness. The siphon is designed to carry the entire flow of the aqueduct of 400
million gallons per day.
A camp accommodating 100 men, and a plant including tramway, bunkers, etc.,
were constructed on the west side of the Tuolumne River near the crossing.
Excavation was started in the main channel in November, 1922, the water being
diverted by means of a cofferdam around the work. This section was rushed with
all possible speed. Early fall rains hampered the work and in December, when
12,000 second feet of water passed down the river, a small section of the cofferdam
was washed out. After concreting this first section of pipe, the river was turned
back into its channel over the pipe and a cofferdam thrown around the east channel.
No unusual difficulties were encountered on the remainder of the work and the
siphon was completed and tested on June 1, 1923, in time to permit the Modesto and
Turlock irrigation districts to close the gates of the Don Pedro Dam and fill the
reservoir for that season's irrigation.
SAN JOAQUIN SIPHON
A 45-mile steel pipe siphon is to be constructed as the last stage of the project
across the San Joaquin Valley from Oakdale Portal to Tesla Portal, connecting the
future Foothill and Coast Range tunnels. To carry the 400 million gallons daily,
which will be released from Moccasin power house, several pipes will be constructed
in the future as necessary.
COAST RANGE DIVISION
From Tesla portal to Irvington Gate -House, a distance of 31 miles, a tunnel
10 feet 3 inches in diameter will be constructed through the Coast Range. It will
be broken at one point by Alameda Creek, which will be crossed by a pipe line one-
half mile long.
BAY DEVELOPMENT
The water which San Francisco obtains from east of the bay is now limited to
about 21 million gallons daily, the capacity flow through one 36-inch pipe. A greater
supply from the developed sources in Calaveras Valley, east of the bay, will be
made available by the conduit across Dumbarton Strait and westward to Crystal
Springs Reservoir. Work now in progress has for its object the construction of a
part of the Hetch Hetchy aqueduct, which, as previously mentioned, will be used
36
temporarily for this purpose by the Spring Valley Water Company immediately
upon its completion.
BAY CROSSING PIPE LINE
A 5-foot steel pipe line has been built, extending from a junction with the
Spring Valley Water Company pipe line, near Irvington, to the east end of Pulgas
Tunnel. The total length of the 5-foot pipe line is 19.4 miles, and the thickness
varies from 5/16-inch to 7/16-inch. In firm and dry ground the pipe is buried,
except portions crossing gullies near the west end, which are supported on steel
trestles resting on concrete piers. Over the marsh lands adjacent to Dumbarton
Straits, pipe is laid on timber trestles and is protected from the weather by board
covering.
The contract for constructing the pipe line was awarded to the Western Pipe
and Steel Company of California on May 18, 1923, for an estimated price of
$2,232,000. Pipe laying was begun on October 20, 1923, and all of the pipe has now
been laid.
PILE TRESTLE
It was necessary to cross the marsh between Newark and Dumbarton Straits
for a distance of about three miles and from the west shore of the bay for nearly
one mile. A pile trestle structure was built which carries the pipe about four feet
above the surface of the marsh.
Contract and specifications for this were prepared and bids received on April 30,
1924. The contract for the construction was awarded to Youdall Construction Com-
pany for the sum of $167,645.
DUMBARTON BRIDGE
Across the shallow portion of Dumbarton Strait the 5-foot diameter pipe is
^^^r,.-->" »* K>k
WKKm wa
*!*wz<$L
^Hpfifi
r^-^^^'B M mil
Bay Development. Five-foot diameter pipe on steel bridge on concrete piers
crossing- of San Francisco Bay at Dumbarton Strait
now carried on a steel bridge of 36 spans, each 105 feet long, extending from the
west shore of the bay to a concrete caisson at the eastern terminal. It is designed
ultimately to carry two pipes, each 6 feet 4 inches inside diameter.
The contract for the steel superstructure was awarded on August 17, 1923, to
the United States Steel Products Company, and the contract for the concrete piers
and caisson on April 1, 1924, to Healy-Tibbits Construction Company. Construction
is still in progress.
The cost under the two contracts will be about $1,465,000.
SUBMARINE SIPHONS
Two navigable channels are crossed by the Bay Crossing Pipe Line, at Dumbarton
Strait and Newark Slough. These will be crossed by cast iron pipe 42 inches inside
diameter and 2 inches thick. The pipe will be laid in a trench so as to be entirely
below the bottom of the bay, and will have flexible joints every 12 feet. The pipe
was manufactured by the United States Cast Iron Pipe and Foundry Company.
In the future, at the east terminal of the bridge, it will be feasible to sink a shaft
and drive a sub-aqueous tunnel to contain the future greater pipes.
PUMP STATION
Near the west shore of Dumbarton Strait a pumping plant has been constructed
to supplement the pressure at which the water is, at present, delivered to the pipe
line, sufficiently to deliver it into the Crystal Springs Reservoir, 290 feet elevation,
through the Pulgas Tunnel.
The station contains three centrifugal pumps, each driven by a 500 horsepower
electric motor. With all three pumps operating, the capacity of the pipe line will be
about 32 million gallons daily.
When the Bay Crossing Pipe Line is connected with the Hetch Hetchy Water
Supply, the use of the Dumbarton pumping station will be discontinued, the gravity
head available at Irvington Gate House being sufficient to give the pipe line a
capacity of about 42 million gallons daily.
PULGAS TUNNEL
This tunnel, which forms the westerly end of the aqueduct from Irvington to
Crystal Springs Reservoir, was completed by Grant Smith and Company in May,
1924, at a total cost of $738,429.23, or $85.11 per lineal foot. It is 8676 feet long,
10 feet 3 inches in height and width inside, and is lined with concrete throughout.
All but 240 feet required timbering. Connection to the two portals is made with
reinforced concrete pipe 337 feet long. A concrete lined outfall canal 906 feet long,
9 feet wide, extends from end of tunnel to the edge of the reservoir.
Plans for the future provide for extending the aqueduct through San Mateo
County to Amazon Reservoir in San Francisco.
CITY RESERVOIRS
The present city reservoirs of the water company have a combined capacity of
125 million gallons, or about three days' domestic water supply, in case the mains
should be broken. Prudent policy dictates that a storage of at least 1,000 million
gallons should be maintained within the city limits. It is proposed that three great
city reservoirs be constructed, known as the Amazon, Glen Park and Balboa Park.
Land has been purchased on two of these sites.
Amazon Reservoir, near the county line, in the saddle on the north side of
Geneva Avenue between Mission Street and Visitacion Valley, will be the terminal
38
reservoir of the Hetch Hetchy aqueduct, which will deliver water into it by gravity
at elevation 250 feet. The capacity of this reservoir will be 300 million gallons or
greater. A tract of land covering 55^4 acres has been selected for this reservoir
site and all but 3% acres is already in the possession of the city.
Glen Park Reservoir site lies in a canyon just below the Twin Peaks Boulevard
and above the old picnic grounds known as Glen Park. At the lower end of the
valley there is an excellent bedrock site for a dam of the same general type as the
Priest Regulating Dam. A dam 150 feet high will provide storage for 500 million
gallons at elevation 385 feet. Over 109 acres of the 184 acres required is already
under city ownership.
Balboa Park Reservoir will be constructed on a tract of land in the possession
of the Spring Valley Water Company between Balboa Park and Westwood Park,
north of Ocean Avenue. The site covers 41 acres. A reservoir with 200 million
gallons of water, at elevation 310 feet, may be constructed here.
Glen Park and Balboa Park reservoirs will be filled by pumping from Amazon
Reservoir. It has been decided that the most economical elevation at which to
receive Hetch Hetchy water in San Francisco is that of the Amazon Reservoir.
About 45 per cent of the total ultimate amount of water used in the city may be
distributed from this latter reservoir without pumping. The elevation of Crystal
Springs Reservoir, 290 feet above the sea, will not permit bringing water by gravity
at an elevation materially greater than that of the Amazon Reservoir.
Quality and Quantity of Water. — The water impounded at Hetch Hetchy and
Lake Eleanor is of the utmost purity and will always remain so. The total area of
watershed aggregates 652 square miles, or about 420,000 acres, all of granite, ranging
in elevation from 3500 feet to over 13,000 feet above sea level, and lying almost
entirely within Yosemite National Park. The precipitation is mostly in the form of
snow, which accumulates during the winter and spring, and whose thawing by the
sun's heat reaches its maximum about June. There is no permanent, all-year residence
on the entire watershed, which is inhabitable only for the three summer months.
There will be no open canal in the aqueduct, the water being conducted through
pipes and tunnels for the entire distance. The water will require no filtration, aera-
tion, chlorination, nor any treatment of any sort.
The Board of Army Engineers, in 1913, reported that there was sufficient water
to supply both the reasonable demand of the bay communities and the reasonable
needs of the Turlock-Modesto Irrigation District for the remainder of this century.
All water measurements are made by the United States Geological Survey.
Finances. — The work was financed up to 1909 by appropriations from the
general tax levy.
In November, 1908, a bond issue of $600,000 was authorized by the voters, largely
to buy lands and water rights.
In January, 1910, a bond issue of $45,000,000 of \ l / 2 per cent bonds was
authorized. Construction has been carried on by these funds. The bonds sold in
August to November, 1921, were converted to 5^4 per cent, sustaining a discount
loss of $2,980,326.55.
The operating receipts of the Hetch Hetchy railroad and power plant, aggregating
$1,600,000, have been placed in a special account from which moneys have been
appropriated by the Finance Committee of the Board of Supervisors to pay interest
on bonds.
On October 7, 1924, a bond issue of $10,000,000 was authorized by the people
by a vote of 20 to 1, to continue the aqueduct construction from Moccasin power
house to the edge of the San Joaquin Valley and to begin construction of tunnel from
the westerly edge of the San Joaquin Valley to connect with the Bay Crossing
pipe line at Irvington.
In about three years it will be necessary to provide an additional $23,000,000
to complete this last tunnel and construct the pipe line across the San Joaquin Valley.
The attitude of the public on the water question was well shown in the elections
of 1910 and 1924, where the vote was in each case over 20 to 1 in favor of the
bonds.
ESTIMATED COSTS OF VARIOUS DIVISIONS OF THE WORK
Financed from Bond Issue of 1909 and 1910, and General Fund
expenditures previous to 1909.
MOUNTAIN DEVELOPMENT
Hetch Hetchy Division
O'Shaughnessy Dam, clearing of Hetch Hetchy Reservoir $ 7,400,000.00
Eleanor Division
Eleanor Dam, clearing of Lake Eleanor Reservoir 373,000.00
Mountain Division
Early Intake Diversion Dam and spillway and headworks
of aqueduct $ 610,000.00
Aqueduct tunnels and appurtenances, Early Intake to
Priest Reservoir (18.84 miles) 10,100.000.00
Total 10,710,000.00
Moccasin Division
Priest Dam and Reservoir $ 930,000.00
Moccasin Tunnel, from Priest Reservoir to head of penstock
lines 1,200,000.00
Penstock lines 2,000,000.00
Power House Building, dwellings, school, etc 1,200,000.00
Power House Machinery 1,135,000.00
Transmission Line, Moccasin to Newark 1,623,000.00
Total $8,088,000.00
Foothill Division
Red Mountain Bar Siphon 262,000.00
General, Utilities, etc., on Mountain Development
Sawmill construction and operation $ 556,000.00
Lower Cherry Power System, construction and operation.... 1,079,000.00
Hetch Hetchy Railroad, construction and operation 5,379,000.00
Munn Sand Plant, Groveland Water Supply, etc 77,000.00
Hospital, construction and operation 221,000.00
Miscellaneous Structures, Water Supply at Groveland 196,000.00
Miscellaneous Roads, Trails, Camps, etc 369,000.00
Boarding House loss 360,000.00
Field Engineering and Administration 381,000.00
Total 8,618,000.00
Total, Mountain Development $35,451,000.00
40
Bay Development
Riveted Steel Pipe Line, 60 inches dia $ 2,408,000.00
Trestle for Steel Pipe Line 198,000.00
Submarine Pipe Lines 599,000.00
Steel Bridge and Piers 1,560,000.00
Gate Valves, Bay Pulgas Pumps, etc 39,000.00
Pulgas Tunnel 757,000.00
Field Engineering and Administration 93,000.00
City Office Engineering and Administration 42,000.00
Total 5,696,000.00
General
Administration, Engineering, Legal, etc. $ 1,415,000.00
Reservoir and Watershed Lands, Water Rights, Rights-of-
Way, Payments to U. S. Government, etc 2,020,000.00
Lands and Rights-of-Way, San Joaquin Division 215,000.00
Lands and Rights of Way, Transmission Line 117,000.00
Lands and Rights-of-Way, Bay Development 221,000.00
Miscellaneous 322,000.00
Total 4,310,000.00
Total Expenditures $45,457,000.00
Less credit for receipts from operation of Hetch Hetchy Railroad, Lower
Cherry Power System, lumber sales, etc 1,907,000.00
Net total expenditures after deducting credits, which may be still further
reduced on final accounting by salvage value of equipment now
on hand $43,550,000.00
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CHRONOLOGY, HETCH HETCHY WATER SUPPLY
Jan. 8, 1900
March 26, 1900
Aug. 12, 1901
July 29, 1901
Oct.
16,
1901
Jan.
20,
1903
February,
1903
Feb.
20,
1903
Dec.
22,
1903
May
11,
1908
Nov.
12,
1908
Jan.
1+,
1910
Feb.
25,
1910
May 12, 1910
May
18,
1910
July,
1912
Sept.
1,
1912
Nov.
25 to
30,
1912
Feb.
9,
1913
March 3, 1913
June 25 to
July 7, 1913
Dec. 19, 1913
July 8, 1914
July 21, 1915
September, 1915
Nov. 24, 1915
Aug. 9, 1916
October
1917
May
6,
1918
Aug.
1,
1919
May
3,
1920
Fall,
1921
Fall,
1921
June
23,
1922
May
18,
1923
Oct.
7,
1924
Aug. 14, 1925
New Charter in effect.
Solicitation of offers of sale of water supplies to City.
City Engineer recommends Tuolumne River.
Appropriations made on water at Hetch Hetchy and Lake Eleanor
by Jas. D. Phelan.
Filings of same at Stockton Land Office.
Phelan's applications denied by Secretary of Interior Hitchcock.
Petition for rehearing, by Franklin K. Lane, City Attorney.
Filings assigned to City.
Application again denied by Secretary of Interior.
Original applications approved by Secretary of Interior Garfield.
Special election authorized construction of Tuolumne System and
issue of $600,000 of bonds, to buy lands, etc.
Bond election, $45,000,000 bonds authorized by vote of 20 to 1.
Order to show cause why Hetch Hetchy should not be eliminated:
Secretary of Interior Ballinger.
Secretary of Interior requested Secretary of War to appoint Board
of Army Engineers to act as Advisory Board.
Board appointed.
"Freeman Plan" of Hetch Hetchy development, published and sub-
mitted to Army Board.
M. M. O'Shaughnessy appointed City Engineer.
Hearings before Secretary of Interior Fisher, attended by Mayor,
City Engineer, City Attorney and consulting engineers.
Army Board report upholds selection of Tuolumne River as
$20,000,000 cheaper than any other system and having greatest
power possibilities.
Conference: City Engineer with Secretary Fisher.
Hearings by committee on the Public Lands, House of Repre-
sentatives.
Hetch Hetchy Grant, or "Raker Bill," signed by President Wilson.
Bids received by Board of Public Works for Contract No. 1, for
constructing a road from Hog Ranch (now Mather) to
Hetch Hetchy.
Began manufacture of lumber at Canyon Ranch.
Began construction of camp buildings at Hetch Hetchy, clearing
of Hetch Hetchy Reservoir site, and construction of Diversion
Tunnel.
Bids received for construction of Hetch Hetchy Railroad.
Bids received for "Drifting Tunnels, Lower Cherry Aqueduct,"
already begun by day labor.
Hetch Hetchy Railroad operation begun.
Lower Cherry Power House began operation.
Contract awarded for construction of Hetch Hetchy Dam.
Contract awarded for construction of Aqueduct Tunnels in
Mountain Division, this work having been carried on so far
by day labor.
Work begun on Priest Dam.
Work begun on Moccasin Power House.
Contract awarded for construction of Pulgas Tunnel.
Contract awarded for construction of Bay Crossing Pipe Line.
Special Election, $10,000,000 bonds authorized to construct Foothill
Tunnels and begin Coast Range Tunnels, vote 20 to 1.
Delivery of power began from Moccasin Power Plant.
46
ELEVATIONS OF VARIOUS POINTS ON WATER PROJECT
13,090 ft. Summit of Mt. Lyell, highest point on watershed.
4,825 ft. Crest of future Lake Eleanor Dam.
4,810 ft. High water, Lake Eleanor Dam.
4,660 ft. Top of present Lake Eleanor Dam.
4,590 ft. Creek bed at Lake Eleanor Dam.
3,812 ft. Crest of future O'Shaughnessy Dam.
3,726.5 ft. Crest of present O'Shaughnessy Dam.
3,500 ft. River bed at O'Shaughnessy Dam.
3,382 ft. Lowest point of foundation, O'Shaughnessy Dam.
2,346 ft. Normal water surface, Early Intake Diversion Dam.
2,326 ft. Floor of tunnel, Early Intake Diversion Dam.
2,240 ft. High water, Priest Regulating Reservoir.
2,170 ft. Floor of tunnel at Priest Portal of 18.8-mile tunnel.
2,145 ft. Floor of inlet of Moccasin Power Tunnel.
924 ft. Nozzles of Moccasin Power House.
888 ft. Floor of Foothill Division Tunnel at Moccasin Creek.
741.6 ft. Floor of Foothill Division Tunnel at Oakdale Portal.
360 ft. Floor of Mt. Diablo Range Tunnel at Tesla Portal.
321 ft. Floor of Mt. Diablo Range Tunnel at Irvington Gate House.
290.5 ft. Floor of Pulgas Tunnel at Redwood Portal.
250 ft. Water surface, Amazon Reservoir, San Francisco.
THE JAMES H. BARRY CO.
1122 MISSION STREET
SAN FRANCISCO, CALIF.
ftG/O
Ccficnfy 7/.0C0aXMga/s
"-CHERRY RESERVOIR (wwr)
a 4 550 ■Capou/ !/ /4S&WX>ftfi
-HETCH HETCHY RES.
7 /i,/mB 3300'
//iSOOOQtiOMjoA
Wafer from fVefcn fre/cny Pes. m/l ' fbir
■ fo For/t/ Intake ant// demand
far porrer trarranfs construct/on of
Canyon Dirrsion of ' aoaedacf
-LOWER CHERRY AQUEDUCT
■ EARLY INTAKE DIVERSION DAM
x Construe/run PonerPtanf (loner Ctierru) 3300 tf)t
LEGEND:—
T T ,. T TUNNELS CONSTRUCTED TO DATE
PIPE LINES CONSTRUCTED TO DATE
TUNNELS TO COMPLETE AQUEDUCT
PIPE LINES TO COMPLETE AQUEDUCT
= = = = AQUEDUCTS FOR FUTURE POWER DEVELOPMENT
■* — —— TRANSMISSION LINE CONSTRUCTED TO DATE
o-o-o -TRANSMISSION LINE - FUTURE EXTENSION
4// eteyofrons refer fo f/etch ttetc fy fofi/r?. nfo'c/r /s epprosmifet/
/Htfe/ ciore VJ6S Do/am an/ 7 73 fee/ ie/an SfCfy fo/um
ETCH HETCHY WATER SUPPLY
OF THE CITY AND COUNTY OF
SAN FRANCISCO, CALIFORNIA.
GENERAL MAP AND PROFILE
DEPARTMENT OF PUBLIC WORKS
!OVED_'^^^ ! ^^^^fet/ut s ^--__CITY ENGI!
JANUARY * 1925
^1925 '
u
B-379
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